VCSEL modules are comprised of a number (i.e. one or a plurality) of VCSEL chips (also called dies) which chips comprise at least one, usually a large number of VCSEL units. The larger these chips the less mounting time and thus mounting costs for the production of VCSEL modules needs to be spent. Therefore, it is particularly beneficial to use as large semiconductor chips in this context as possible as long as they can be soldered with a good quality. Firstly, larger chips reduce the amount of lost wafer area due to sawing lanes and rims of the chips. Secondly, fewer individual soldered steps, i.e. pick-and-place steps, are necessary. VCSEL chips currently have maximum sizes varying between 0.8 mm×0.8 mm up to 5 mm×5 mm.
The sizes of VCSEL chips are mainly limited by the current that runs through them. As the efficiency of VCSELs has improved enormously (even apart from the sizes of VCSEL chips), operational currents of 15 A in cw (continuous wave) operation and even 30 A in pulsed operation can be considered normal for a chip of the size of 4 mm2. Larger chips, for instance, with a size of 9 mm2 may result in currents well above 50 A. However, for a laser driver with a fixed electrical power of, for instance, 1000 W it is beneficial to operate at relatively moderate currents. In addition, the size of the electrical connections from such driver to the VCSEL module and inside of the VCSEL module scale up with the operation current and become more and more bulky, heavy, and inflexible.
For small VCSEL chips, the operation current and voltage can be tailored by connecting several chips in parallel and others in series. For larger chips however, the current is the limiting factor of size, because on the chip level all VCSEL units are operated in parallel. This implies that there is a certain limit of size to VCSEL chips inside VCSEL modules which limit also restricts the effectivity of mounting processes of the VCSEL chips.
Therefore, it is an object of the invention to provide for a possibility of more effectively providing a VCSEL module of the above-mentioned kind, in particular by overcoming the current limit of the size of the VCSEL chips.